macOS: increase minimum supported OS from 10.9 to 10.13

The most recent macOS SDK fails to link when the deployment target is set to 10.9.

platform/xcode/liblove.xcodeproj/project.pbxproj

@@ -5511,7 +5511,7 @@
 				);
 				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				LIBRARY_SEARCH_PATHS = "";
-				MACOSX_DEPLOYMENT_TARGET = 10.9;
+				MACOSX_DEPLOYMENT_TARGET = 10.13;
 				ONLY_ACTIVE_ARCH = NO;
 				SDKROOT = macosx;
 				USE_HEADERMAP = NO;
@@ -5577,7 +5577,7 @@
 				);
 				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				LIBRARY_SEARCH_PATHS = "";
-				MACOSX_DEPLOYMENT_TARGET = 10.9;
+				MACOSX_DEPLOYMENT_TARGET = 10.13;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = macosx;
 				USE_HEADERMAP = NO;
@@ -5716,7 +5716,7 @@
 				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				LIBRARY_SEARCH_PATHS = "";
 				LLVM_LTO = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.9;
+				MACOSX_DEPLOYMENT_TARGET = 10.13;
 				ONLY_ACTIVE_ARCH = NO;
 				SDKROOT = macosx;
 				USE_HEADERMAP = NO;

platform/xcode/love.xcodeproj/project.pbxproj

@@ -564,7 +564,7 @@
 				INFOPLIST_FILE = "love-Info.plist";
 				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				LD_RUNPATH_SEARCH_PATHS = "@loader_path/../Frameworks";
-				MACOSX_DEPLOYMENT_TARGET = 10.9;
+				MACOSX_DEPLOYMENT_TARGET = 10.13;
 				ONLY_ACTIVE_ARCH = YES;
 				PRODUCT_NAME = love;
 				SDKROOT = macosx;
@@ -640,7 +640,7 @@
 				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				LD_RUNPATH_SEARCH_PATHS = "@loader_path/../Frameworks";
 				LLVM_LTO = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.9;
+				MACOSX_DEPLOYMENT_TARGET = 10.13;
 				ONLY_ACTIVE_ARCH = NO;
 				PRODUCT_NAME = love;
 				SCAN_ALL_SOURCE_FILES_FOR_INCLUDES = YES;
@@ -874,7 +874,7 @@
 				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				LD_RUNPATH_SEARCH_PATHS = "@loader_path/../Frameworks";
 				LLVM_LTO = YES;
-				MACOSX_DEPLOYMENT_TARGET = 10.9;
+				MACOSX_DEPLOYMENT_TARGET = 10.13;
 				ONLY_ACTIVE_ARCH = NO;
 				PRODUCT_NAME = love;
 				SCAN_ALL_SOURCE_FILES_FOR_INCLUDES = YES;